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240. LABOUR and intention to imitate voices, doth conduce much to imitation: and therefore we see that there be certain pantomimi, that will represent the voices of players of interludes so to life, as if you see them not you would think they were those players themselves; and so the voices of other men that they hear.
241. THERE have been some that could counterfeit the distance of voices, which is a secondary object of hearing, in such sort, as when they stand fast by you, you would think the speech came from afar off, in a fearful manner. How this is done may be further inquired. But I see no great use of it but for imposture, in counterfeiting ghosts or spirits.
Experiments in consort touching the reflexion of sounds.
THERE be three kinds of reflexions of sounds; a reflexion concurrent, a reflexion iterant, which we call echo; and a super-reflexion, or an echo of an echo; whereof the first hath been handled in the title of magnitude of sounds: the latter two we will now speak of.
242. THE reflexion of species visible by mirrors you may command; because passing in right lines they may be guided to any point: but the reflexion of sounds is hard to master; because the sound filling great spaces in arched lines, cannot be so guided: and therefore we see there hath not been practised any means to make artificial echos. And no echo already known returneth in a very narrow room.
243. THE natural echos are made upon walls, woods, rocks, hills, and banks; as for waters, being near, they make a concurrent echo; but being farther off, as upon a large river, they make an iterant echo: for there is no difference between the concurrent echo and the iterant, but the quickness or slowness of the return. But there is no doubt but water doth help the delation of echo; as well as it helpeth the delation of original sounds.
244. IT is certain, as hath been formerly touched, that if you speak through a trunk stopped at the far
ther end, you shall find a blast return upon your mouth, but no sound at all. The cause is, for that the closeness which preserveth the original, is not able to preserve the reflected sound: besides that echos are seldom created but by loud sounds. And therefore there is less hope of artificial echos in air pent in a narrow concave. Nevertheless it hath been tried, that one leaning over a well of twenty-five fathom deep, and speaking, though but softly, yet not so soft as a whisper, the water returned a good audible echo. It would be tried, whether speaking in caves, where there is no issue save where you speak, will not yield echos as wells do.
245. THE echo cometh as the original sound doth, in a round orb of air: it were good to try the creating of the echo where the body repercussing maketh an angle as against the return of a wall, etc. Also we see that in mirrors there is the like angle of incidence, from the object to the glass, and from the glass to the eye. And if you strike a ball side-long, not full upon the surface, the rebound will be as much the contrary way: whether there be any such resilience in echos, that is, whether a man shall hear better if he stand aside the body repercussing, than if he stand where he speaketh, or any where in a right line between, may be tried. Trial likewise would be made, by standing nearer the place of repercussing than he that speaketh; and again by standing farther off than he that speaketh; and so knowledge would be taken, whether echos, as well as original sounds, be not strongest near hand.
246. THERE be many places where you shall hear a number of echos one after another: and it is when there is variety of hills or woods, some nearer, some farther off: so that the return from the farther, being last created, will be likewise last heard.
247. As the voice goeth round, as well towards the back, as towards the front of him that speaketh; so likewise doth the echo: for you have many back echos to the place where you stand.
248. To make an echo that will report three, or four, or five words distinctly, it is requisite that the
body repercussing be a good distance off: for if it be near, and yet not so near as to make a concurrent echo, it choppeth with you upon the sudden. It is requisite likewise that the air be not much pent: for air at a great distance pent, worketh the same effect with air at large in a small distance. And therefore in the trial of speaking in the well, though the well was deep, the voice came back suddenly, and would bear the report but of two words.
249. FOR echos upon echos, there is a rare instance thereof in a place which I will now exactly describe. It is some three or four miles from Paris, near a town called Pont-Charenton; and some bird-bolt shot or more from the river of Sein. The room is a chapel or small church. The walls all standing, both at the sides and at the ends. Two rows of pillars, after the manner of isles of churches, also standing; the roof all open, not so much as any embowment near any of the walls left. There was against every pillar a stack of billets above a man's height; which the watermen that bring wood down the Sein in stacks, and not in boats, laid there, as it seemeth, for their ease. Speaking at the one end, I did hear it return the voice thirteen several times; and I have heard of others, that it would return sixteen times: For I was there about three of the clock in the afternoon
and it is best, as all other echos are, in the evening. It is manifest that it is not echos from several places, but a tossing of the voice, as a ball, to and fro; like to reflexions in looking-glasses, where if you place one glass before and another behind, you shall see the glass behind with the image, within the glass before; and again, the glass before in that; and divers such super-reflexions, till the species speciei at last die. For it is every return weaker and more shady. In like manner the voice in that chapel createth speciem speciei, and maketh succeeding super-reflexions; for it melteth by degrees, and every reflexion is weaker than the former: so that if you speak three words, it will, perhaps, some three times report you the whole three words; and then the two latter words for some
times; and then the last word alone for some times; still fading and growing weaker. And whereas in echos of one return, it is much to hear four or five words; in this echo of so many returns upon the matter, you hear above twenty words for three.
250. THE like echo upon echo, but only with two reports, hath been observed to be, if you stand between a house and a hill, and lure towards the hill. For the house will give a back echo; one taking it from the other, and the latter the weaker.
251. THERE are certain letters that an echo will hardly express; as S for one, especially being principal in a word. I remember well, that when I went to the echo at Pont-Charenton, there was an old Parisian, that took it to be work of spirits, and of good spirits. For, said he, call Satan, and the echo will not deliver back the devil's name; but will say, va t'en; which is as much in French as apage, or avoid. And thereby I did hap to find, that an echo would not return S, being but a hissing and an interior sound.
252. ECHOS are some more sudden, and chop again as soon as the voice is delivered; as hath been partly said: others are more deliberate, that is, give more space between the voice and the echo; which is caused by the local nearness or distance: some will report a longer train of words, and some a shorter; some more loud, full as loud as the original, and sometimes more loud, and some weaker and fainter.
253. WHERE echos come from several parts at the same distance, they must needs make, as it were, a choir of echos, and so make the report greater, and even a continued echo; which you shall find in some hills that stand encompassed theatre-like.
254. IT doth not yet appear that there is refraction in sounds, as well as in species visible. For I do not think, that if a sound should pass through divers mediums, as air, cloth, wood, it would deliver the sound in a different place from that unto which it is deferred; which is the proper effect of refraction. But majoration, which is also the work of refraction,
appeareth plainly in sounds, as hath been handled at full, but it is not by diversity of mediums.
Experiments in consort touching the consent and dissent between visibles and audibles.
WE have obiter, for demonstration's sake, used in divers instances the examples of the sight and things visible, to illustrate the nature of sounds: but we think good now to prosecute that comparison more fully.
Consent of visibles and audibles.
255. BOTH of them spread themselves in round, and fill a whole floor or orb unto certain limits; and are carried a great way: and do languish and lessen by degrees, according to the distance of the objects from the sensories.
256. BOTH of them have the whole species in every small portion of the air, or medium, so as the species do pass through small crannies without confusion: as we see ordinarily in levels, as to the eye; and in crannies or chinks, as to the sound.
257. BOTH of them are of a sudden and easy generation and dilation; and likewise perish swiftly and suddenly; as if you remove the light, or touch the bodies that give the sound.
258. BOTH of them do receive and carry exquisite and accurate differences; as of colours, figures, motions, distances, in visibles; and of articulate voices, tones, songs, and quaverings, in audibles.
259. BOTH of them, in their virtue and working, do not appear to emit any corporal substance into their mediums, or the orb of their virtue; neither again to raise or stir any evident local motion in their mediums as they pass; but only to carry certain spiritual species; the perfect knowledge of the cause whereof, being hitherto scarcely attained, we shall search and handle in due place.
260. BOTH of them seem not to generate or produce any other effect in nature, but such as appertaineth to their proper objects and senses, and are otherwise barren.